package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private RedissonClient redissonClient;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    // 异步处理线程池
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    // 阻塞队列
    ArrayBlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    // 在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    // 提取代理对象到
    private IVoucherOrderService proxy;

    // 内部类用户处理异步任务
    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    // 获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 创建订单
                    handlerVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("订单信息异常，",e);
                }
            }
        }

        private void handlerVoucherOrder(VoucherOrder voucherOrder) {
            // 获取用户
            Long userId = voucherOrder.getUserId();
            // 创建锁对象
            // 使用redisson创建锁对象
            RLock lock = redissonClient.getLock("lock:order:" + userId);
            // 尝试获取锁
            boolean flag = lock.tryLock();
            if (!flag) {
                // 获取锁失败则直接返回错误
                log.error("不可重复下单");
                return;
            }
            try {
                // 获取spring动态代理对象
                //注意：由于是spring的事务是放在threadLocal中，此时的是多线程，事务会失效
                proxy.createVoucherOrder(voucherOrder);
            } catch (IllegalStateException e) {
                throw new RuntimeException(e);
            } finally {
                // 释放锁
                lock.unlock();
            }
        }
    }

    /**
     * 抢购优惠券
     *
     * @param voucherId
     * @return
     */
    @Override
    public Result sechillVoucher(Long voucherId) {
        // 获取用户
        Long userId = UserHolder.getUser().getId();
        long orderId = redisIdWorker.nextId("order");
        // 1.执行lua脚本
        Long res = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId)
        );
        // 2.判断结果是否为0
        int r = res.intValue();
        if (r != 0) {
            // 不为0代表没用购买资格
            return Result.fail(r == 1 ? "库存不足" : "不可重复下单");
        }
        // 保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        // 填充用户信息
        voucherOrder.setVoucherId(orderId);
        voucherOrder.setUserId(userId);
        voucherOrder.setVoucherId(voucherId);
        // 让如阻塞队列
        orderTasks.add(voucherOrder);
        // 获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        // 3.返回订单id
        return Result.ok(orderId);

    }
    /*@Override
    public Result sechillVoucher(Long voucherId) {
        // 1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀尚未开始！");
        }
        // 3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束！");
        }
        // 4.判断库存是否充足
        if (voucher.getStock() < 1) {
            return Result.fail("库存不足！");
        }
        Long userId = UserHolder.getUser().getId();
        // 创建锁对象
        // SimpleRedisLock lock = new SimpleRedisLock("order" + userId, stringRedisTemplate);
        // 使用redisson创建锁对象
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 尝试获取锁
        boolean flag = lock.tryLock();
        if (!flag) {
            // 获取锁失败则直接返回错误
            return Result.fail("不可重复下单");
        }
        try {
            // 获取spring动态代理对象
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            // 释放锁
            lock.unlock();
        }
    }*/

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 一人一单逻辑
        // 获取用户id(从voucherOrder中收集)
        Long userId = voucherOrder.getUserId();
        int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        // 判断是否存在
        if (count > 0) {
            // 标识该用户已经购买过了
            log.error("您已经购买过一次了");
            return;
        }
        // 5.扣减库存(使用乐观锁解决库存超卖问题)
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0) // where voucher_id = ? and stock > 0
                .update();
        if (!success) {
            log.error("库存不足");
            return;
        }
        // 6.创建订单
        // 返回
        save(voucherOrder);
    }
}
